US3860342A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual-wavelength scanning doppler velocimeter
Assignee: National Aeronautics and Space Administration
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Filing: 1973-04-18
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Granted: 1975-01-14
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Expires: 1993-04-18
Abstract
Abstract A laser Doppler velocimeter for simultaneously measuring localized orthogonal velocity components in a fluid stream without perturbation of the flowfield wherein a first pair of beams of a first common wavelength and a second pair of beams of a second common wavelength are derived from a single laser source, directed along a single optical axis such that the respective beams of each pair of beams are disposed parallel to the axis, symmetrically about the axis, and are positioned orthogonally about the axis relative to each other. The four beams are then focused upon a selected test volume within the flowfield and light scattered at that point is collected by an appropriate optical system and focused onto photo-detectors which develop electrical output signals commensurate with the orthogonal velocity components at the test point.
Inventors
- 👤 Kenneth L Orloff
- 👤 George R Grant
- 👤 Jr William D Gunter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:42
CPC Classifications
G; G01; G01S; G01S17/00; G01S17/02; G01S17/50; G01P; G01P3/00; G01P3/36; G01P3/366; G01P5/00; G01P5/26
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
277 words
Doppler velocimeter apparatus for sImultaneously measuring fluid velocity components at points within a fluid stream, comprising: a light source for developing one light beam having a first wavelength and another light beam having a second wavelength; light splitting means for dividing said one light beam into first and second parallel light beams respectively disposed on each side of an optical axis, and for dividing said other light beam into parallel third and fourth light beams respectively disposed on opposite sides of said axis, said first and second light beams lying in a first plane including said axis, and said third and fourth light beams lying in a second plane including said axis; light focusing means disposed along said axis and operative to focus said first, second, third and fourth light beams at a common point within the fluid stream, the light of said beams being scattered by the stream at said common point; collecting means for collecting the light scattered at said common point; first light detecting means responsive to light directed thereupon and operative to develop first electrical signals commensurate therewith; second light detecting means responsive to light directed thereupon and operative to develop second electrical signals commensurate therewith; and light separating means for separating the collected scattered light of said first wavelength from the collected scattered light of said second wavelength, and for directing the first mentioned separated light onto said first light detecting means and for directing the second mentioned separated light onto said second light detecting means, whereby said first electrical signals are representative of a first fluid velocity component and said second electrical signals are representative of a second fluid velocity component.
Claim 2
Dependent Claim
277 words
Doppler velocimeter apparatus for sImultaneously measuring fluid velocity components at points within a fluid stream, comprising: a light source for developing one light beam having a first wavelength and another light beam having a second wavelength; light splitting means for dividing said one light beam into first and second parallel light beams respectively disposed on each side of an optical axis, and for dividing said other light beam into parallel third and fourth light beams respectively disposed on opposite sides of said axis, said first and second light beams lying in a first plane including said axis, and said third and fourth light beams lying in a second plane including said axis; light focusing means disposed along said axis and operative to focus said first, second, third and fourth light beams at a common point within the fluid stream, the light of said beams being scattered by the stream at said common point; collecting means for collecting the light scattered at said common point; first light detecting means responsive to light directed thereupon and operative to develop first electrical signals commensurate therewith; second light detecting means responsive to light directed thereupon and operative to develop second electrical signals commensurate therewith; and light separating means for separating the collected scattered light of said first wavelength from the collected scattered light of said second wavelength, and for directing the first mentioned separated light onto said first light detecting means and for directing the second mentioned separated light onto said second light detecting means, whereby said first electrical signals are representative of a first fluid velocity component and said second electrical signals are representative of a second fluid velocity component.
Claim 3
Dependent Claim
47 words
Doppler velocimeter apparatus as recited in claim 1 wherein said light source includes, a laser device for developing a beam of coherent radiation having several discrete radiation lines, and light dispersing means for separating said beam of coherent radiation into said one beam and said other beam.
Claim 4
Dependent Claim
112 words
Doppler velocimeter apparatus as recited in claim 1 wherein said light focusing means and said light collecting means are embodied in a single optical system for collecting back-scattered light, and wherein said light separating means includes a first reflector having dichroic characteristics and a second reflector, both of which are positioned along said optical axis between said light splitting means and said light focusing means, said first reflector being operative to reflect scattered light of said first wavelength onto said first detecting means and to transmit light of said second wavelength onto said second reflector, said second reflector being operative to reflect light of said second wavelength onto said second detecting means.
Claim 5
Dependent Claim
55 words
Doppler velocimeter apparatus as recited in claim 1 wherein said light focusing means comprises a lens combination including a negative achromatic lens and a positive achromatic lens, at least one of said lens being movable along said optical axis relative to the other lens to permit variation of the spatial position of said common point.
Claim 6
Dependent Claim
42 words
Doppler velocimeter apparatus as recited in claim 1 wherein said light focusing means is positioned on one side of said fluid stream and wherein said light collecting means is positioned on the opposite side of said stream to collect forward scattered light.
Claim 7
Dependent Claim
65 words
Doppler velocimeter apparatus as recited in claim 5 wherein said light focusing means and said light collecting means each include means for permitting their respective focal points to be varied, and said velocimeter apparatus further includes control means for synchronously varying the focal points of said light focusing means and said light collecting means so that the two focal points are at all times coincident.
Claim 8
Dependent Claim
32 words
Doppler velocimeter apparatus as recited in claim 5 wherein said light collecting means includes means for sensing the poSition of said common point and for automatically focusing said light collecting means thereupon.
Claim 9
Dependent Claim
84 words
Doppler velocimeter apparatus as recited in claim 1 wherein said light splitting means includes, a first splitter block positioned to receive said one light beam and to split it into said first light beam and said second light beam whereby said first and second light beams lie in a vertical plane, and a second splitter block for receiving said other light beam and dividing it into said third and fourth light beams whereby said third and fourth light beams lie within a horizontal plane.
Claim 10
Dependent Claim
60 words
Doppler velocimeter apparatus as recited in claim 8 wherein said light splitting means further includes a light combining means for combining the vertically related first and second light beams and the horizontally related third and fourth light beams in a manner whereby all are directed in parallel to each other and respectively disposed in orthogonal positions about said optical axis.
Claim 11
Dependent Claim
112 words
Doppler velocimeter apparatus as recited in claim 9 wherein said light focusing means and said light collecting means are embodied in a single optical system for collecting back-scattered light, and wherein said light separating means includes a first reflector having dichroic characteristics and a second reflector, both of which are positioned along said optical axis between said light splitting means and said light focusing means, said first reflector being operative to reflect scattered light of said first wavelength onto said first detecting means and to transmit light of said second wavelength onto said second reflector, said second reflector being operative to reflect light of said second wavelength onto said second detecting means.
References Cited (Backward Citations)
US3730625A
Cited
US3723004A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |